It is the debate of the moment. In a risk-filled world, are democracies justified in turning to large-scale state surveillance, at home and abroad, to fight complex and unconventional threats? Or is the emergence of the surveillance state and the awesome powers it derives from information technology a new and pervasive threat to our basic freedoms? For some the answer is obvious: the threats more than justify the current surveillance system, and the laws and institutions of democracies are more than capable of balancing the needs of individual privacy with collective security. For others, we are in peril of sacrificing to state surveillance and exaggerated terrorist threats the civil liberties that guarantee citizens' basic freedoms.